I made the folding mechanism for my stainless steel blade. I've printed both steel and plastic version of the knife. The folding mechanism is unusual: simple and sturdy. Check out animation of the folding mechanism (https://youtu.be/2RWEbohZ_Mg). The knife can be printed without support. But I reccomend to add support for the pins of the blade. I included OpenSCAD source. Have fun!